Circuit breaker



May l2, 319%. J. B. MacNExLL @$304,628

CIRCUIT BREAKER Filed Nov. 6. 1928 Patented May 12, 1931 UNITED STATES PATENT ori-ICE JOHN B. MACNEILL, F WILKINSBURG, PENNSYLVAN IA., ASSIGNOR T0 WESTINGHO'US ELECTRIC & MANUFACTURING-COMPANY, A CORPORATION 0F PENNSYLVANIA CIRCUIT BREAKER Application led November 6, 1928. Serial No. 317,499.

My' invention relates to circuit interrupters and particularly to the contact members therefore. t

Difficulty is experienced in closing a c1rcuit interrupter when a short-circuit current is present in the system because of a magnetic force developed in the vicinity of the contacts which opposes the closing force of the operating mechanism and, when the distance to be-travelled by the moving contacts,fbefore they fully engage the stationary contacts, is large, this force may rise Vto a value suiicient to overcome the closing force and prevent the moving contacts from reaching completely engaging positions.

This distance that the movable contacts must travel before they are in completely engaging position varies according to the amount of lead the arcing contact is given over the main contact Which is regulated by the amountof current and voltage to be interrupted.

It is one object of my invention to provide arcing contacts for a circuit interrupter that shall be positioned a short distance in advance of the main contacts, when in completely disengaged position, and that shall travel a distance considerably in advance thereof when the circuit interrupter is being opened.

Another object of my invention is to provide a lcircuit interrupter with arcing contacts of the above-described type that shall be moved, to follow the cooperating movable contact member, by a force developed in a current path associated with the said arcing contact.

A further object of my invention'is to provide a circuit interrupter with contacts of the above-described type that shall remain in engagement for a period that varies directly with the amount of current iiowing in the system at the time of .interruption. y

My invention will now be described in detail, reference being had to the drawings, in which;

Figure 1 is a view, in elevation, of a particular embodiment of my invention in closed position;

Fig. 2 is a view, in elevation, of the embodiment of my invention shown in Fig. 1, with thecontacts separated.

My invention comprises, in general, a lift rod 1 supporting a cross bar 2 that has a main current-carrying contact 3 and an arcing contact 4 -on each end thereof.

In the figures, the right-hand portion of the cross bar 2 is omitted, the contacts thereof being like the left-hand contacts that appear in the ligures.

The main contact 3 is laminated and so disposed that the ends of the laminations engage the face of a main stationary contact 5 that is supported on an insulator 6 and has an arm 7 projecting therefrom upon which is pivoted a movable contact member 8 by means of a pin 9. A double-acting spring 11 is mounted upon the pin 9 and its ends are hooked over the arm 7. in such manner that a pin 12 on an arm of the arcing contact member 8 is biased thereby to neutral position, asl shown in Fig. 2.

The respective ends of a flexible conductor 13 are fastened to the arm 7 and to the contact member 8 by screws 14 to constitute ya loop vor short circuit for the current transferred vthereto When the contacts 3 and 5 are separated. The magnetic flux about the loop circuit provides a repellent force that causes the contact member 8 to move in a clockwise direction about the pin 9 to a position substantially as .shown in dotted lines in Fig. 1.

Such an arrangement causes the arcing Contact member 8 to follow the arcing -tip 4 a considerable distance beyond its neutral position and, as the amount of travel is proportional to the repellent force set up in the loop, it Will be seen that this downward movement will be proportional to the amount of current-iiowing therein.

During this movement, the pin l2 has moved the bottom arm of spring 11 away from the arm 7 so that, after the current is finally broken and the repellent force no longer acts the'spring 11 will bias the pin 12 to cause the contact member 8 to return to its neutral position.

When the circuit interrupter is being A closed, the contact 4 will first complete the circuit against the contact member 8 and move it in a counter-clockwise direction until the main contacts are in completely engaged position, which is that shown in Fig. l. 'In this'position, the pin l2 has moved the top arm of the spring 11 away from arm 7 to thereby apply a biasing force to the contact member'S when the breaker is tripped, that will turn it in a clockwise di- -rection until the current has been transshort lead of the arcing contact'beyond the engaged position of the main contact, so that the circuit interrupter will be closed before a force, such as that set up by a short-circuit current, can become effective.

My invention is further novel by providing a distance of engagement of the arcing contact, that varies in accordance with the current flowing in the system, which variation in distance is directly responsive to the amount of current present at the arcing contacts. l y

While I have shown a single embodiment of my invention, I do not wish to be limited to this specific structure, as my invention may be employed in airbreak circuit interrupters aswell as in oil-break circuit interrupters, and applied to either -the main contacts or to arcing contacts, as herein shown. It is also feasible to have both pairs of arcing contacts constructed as is the one here described. I, therefore, do not wish my invention to be limited except as limitations may be imposed by the prior art.

I claim as my invention:

, 1. The combination with a main contact for a circuit interrupterv having an arcing contact associated therewith, of a spring for retaining the arcing' contact in a neutral position beyond the main contact when said members are in 'open circuit position, and a current path so associated with the arcing contact that said contact -is biased beyond its neutral position when the 'circuit interrupter isbeing actuated to open position.

2. In a circuit interrupter having a plurality of separable pairs of main contact members, of a pair of arcing contact members associated with each pair of main contact members, one arcing contact member of each pair being flexibly mounted, springs for retaining the last said contact members main contact members, a spring on each contact member for retaining it in a neutral position in advance of the main contact` members, when said members are separated and a current-affected loop associated with each of the contact members which forces the said contact members beyond their neutral positions when the current has been shifted to said loop after the main contacts have separated.

fl. The combination with a pair of stationary contact members and a bridging member therefor, of an arcing tip connected to each of the said contact members, a pair of cooperating arcing tips associated with the bridging member and a current-actuating conducting loop associated with the first said arcing tips for providing a downward force to cause them to followthe arcing tips on the bridging members when current is fiowing in the loop after the main' contactsv are separated. v

The combination with a pair of statlonary contact members and a bridging member therefor, of an arcing tip connectedy to each ofthe said contact members, a pairof cooperating arcing tips associated with the bridging member, biasing means on the first said arcing tips adapted to retain/them in a neutral positlon in advance `of the stationary contact members when said Contact members are separated, and means associated with the first said arcing tips adapted to provide a magnetic repellent force that actuates them downwardly against the force .of the said neutralizing biasing means to provide a larger separation of the bridging member Vfrom the contact members before the arcing tips become disengaged, than the separation vthereof when the arcing tips become engagedv during the closing movement.

6. The combination with two relatively movablemain contact members, of an arcing contact member associated therewith and flexibly connected to one of the said main contact members, a spring for retaining the arcing contact member in a neutral position in advance of the main contact member, when said contact members are separated, and a U-shaped fiexible conductor forming a current path to the arcin contact member for moving it downwar ly beyond said neutral position when current is owing throu h said U-shaped conductor.

7. contact for a circuit interrupter characterized by'the association of a substantialiy U-shaped current path and a neutralizing spring whereby the contact will be eii'ective through a greater distance in the opening than in the closing movement of the circuit interrupter.

8. The combination, in a circuit interrupter having main separable contact members, of auxiliary^contact members associated therewith, a current-carry loop and a biasing means associated with the auxiliary contact members for causing the auxiliary ontact members to be in engagement over a greater distance during the opening than during the closing movement of the main contact members. 4

9. The combination with cooperating contact members of a circuit interrupter, of a current path associated therewith for providing a movement to one of the contact members to retain it in engagement with its cooperating moving contact member through a distance that is pro ortional to the amount of current fiowing t rough said current path.

10. A plurality of contacts for a circuit interrupter characterized by the association of a substantially U-shaped current path and a neutralizing spring with each contact whereby 'the contactsV will be effective throu h a greater distance in the openin than 1n the closing movement of the circuit interru'pter. l

In testimony whereof, I have hereunto subscribed my name this 26th day of October, 1928. f

' JOHN B. MACNEILL. 

